In the dark of space, enlightenment waits David Grinspoon, DAVID GRINSPOON, curator of astrobiology at the Denver Museum of Nature & Science, is the author of "Lonely Planets: The Natural Philosophy of Alien Life" (Harper Perennial, 2004).

War's stunning price tag Linda Bilmes and Joseph Stiglitz, LINDA BILMES, a former assistant secretary of Commerce, teaches public finance at the Kennedy School of Government at Harvard. JOSEPH STIGLITZ is a professor at Columbia University. He won the Nobel Prize in economics in 2001.